Патент USA US2091118код для вставки
Allg- 24, 1937. l ` E. c. HERTHEL ET AL' \ 2,091,113 ART OF CRACKING~ Filed April 1, 193s (br/fon l VEN ORS 62' mia/? gd ene C', #erf/fel fw„QW,w 1 ¿aww 2,091,118 Patented Aug. 24, 1937 UNITED STATES PATENT OFFICE 2,091,118 ART OF CRACKING Eugene C. Herthel, Flossmoor, Ill., and Carlton L. Schmidt, Hammond, Ind., assignors to Sin clair Reñning Company, New York, N. Y., a corporation of Maine Application April 1, 1933, Serial No. 663,954 2 Claims. This invention relates to improvements in the manufacture of motor fuel gasoline ‘oy operations in which a stream of higher boiling petroleum oil is heated to cracking temperatures, upwards 5 of 925° F. for example, under superatmospheric pressure, upwards of 200 lbs. per square inch for example, and then discharged, with reduction of pressure, into a separating receptacle in which a vapor fraction is separated from. tar. The im provements of this invention make possible a reduction in the proportion of tar made and, at the same time, the production of a cleaner tar or, in another aspect, an increase in the recovery of liquid products other than tar conjointly with 15 the production of a tar of improved quality. The tar separated in the separating receptacle in operations of this character includes tar con stituents produced by cracking and may include tar lconstituents of stocks supplie-d to the opera tion as well as varying proportions of oil con 20 stituents. Normally the tar is the least valuable of the products of such operations and conse~ quently the oil content of the tar made repre sents a double loss to the extent that such oil might be recovered as a part of the more valuable 25 liquid products other than tar in that it repre sents at the same time an increase in the pro portion of tar made and a decrease in the pro portion of liquid products other than tar made. The obvious economic necessity for minimizing 30 the proportion of tar made has provoked various proposals intended to'accomplish this end. Ex cepting those involving ultimate reduction of the tar made to coke, these proposals have been characterize-d by the production of dirtier and 35 consequently less valuable tars. This invention makes possible a reduction in the proportion of tar made Without involving this disadvantage. According to the present invention, a stream of high boiling oil is heated to a cracking tempera 40 ture under superatmospheric pressure, the presu sure on the hot oil products of this heating op eration is reduced and they are then introduced into a separating receptacle in which the hot oil products are cooled by the introduction, into (Cl. 1536-58) receptacle and a vapor fraction and a liquid tar are separately discharged from the separating receptacle. By utilizing an oil fraction of the speciñed characteristics as the cooling medium in the separating receptacle an unusually complete stripping of oil constituents from the separated liquid tar is effected, the absence from the cool ing‘medium of those constituents of the hot oil products discharged into the separating recep tacle from the heating operation of boiling range 10 abutting that of the tar rendering this cooling medium a highly effective distillation medium,v upon vaporization, by reducing the partial pres sure of the highest boiling of the oil constituents separated as vapors in the separating receptacle. 15 At the same time, further cracking or polymeriza tion of constituents of the liquid tar separated in the separating receptacle is minimized bythe maintenance of a minimum volume~ of separated> liquid tar within the separating receptacle thus enabling, in conjunction with the improved 20 stripping of oil constituents from the tar, the ` production of a more concentrated and at the 1 same time a cleaner tar. For example, the in vention makes it possible to reduce the propor tion of tar made as much as 50% or more, or in 25 terms of tar concentration to» reduce the gravity of the tar, for example, from 5° A. P. I. to ~-2° A. P. I., and at the same time to produce a tar having a B. S. content, for example, oi 0.25% as compared to 1.00%, such reduced proportion 30 or increased `concentration of tar made being reflected in improved recovery of liquid products other than tar. v ~ The invention will be further described in con.-r nection with the accompanying drawing which 35 illustrates,` diagrammatically and conventionally, in `elevation and partly in section with parts broken away, one form of apparatus appropriate for practice of the invention. The apparatus illustrated comprises a heating 40 furnace l, a separating tower 2, a fractionating tower 3, a condenser 4 and a receiver 5. High boiling oil to be cracked, stock supplied from an extraneous source through connection t’- or the 45 the separating receptacle, of a liquid oil fraction higher boiling fraction or part of the higher >boil vaporizing substantially completely under the conditions prevailing in the separating receptacle ing fraction separated as a condensate/in. frac and which is substantially free from those con 55 stituents of the expanded hot `oil products of boiling range next lower than, that is abutting, that of the tar to be separated in the separating receptacle, that minimum volume of separated liquid tar necessary to maintain liquid discharge therefrom is maintained within the separating tionating tower 3 suppliedthrough connections 1 and 8 or a mixture of the two, is forced, by means of pump 9, through the heating coil I0, 50 arranged in the heating furnace I, and thence„ through the pressure reducing valve Il in trans fer connection l2, into the separating tower 2. High boiling oil supplied through connection v6 can be supplied tothe heating coil l0 directly 2 2,091,118 through connection 3l, or, when condensate is supplied from the lower part of tower 3 to the heating coil IG, through connection 32. The stream of oil fiowing through the heating coil I0 is heated to a temperature, for example, of 945°-975° F. under a superatmospheric pressure, for example, of 30G-600 lbs. per square inch as discharged therefrom. VThe pressure on the hot oil products discharged from the heating coil I0 is reduced as they pass through valves II and connection I‘I, these higher boiling constituents being separated as the higher boiling condensate separated in the fractionating tower 3 and dis charged therefrom through connection 'I. The they are then introduced into the separating absence of these intermediate constituents from the stock introduced into the separating tower 2 tower 2 maintained under a pressure, for exam as a cooling medium effects the unusually com ple, of 25-'75 lbs. per square inch. A cooling medium is introduced into the separating tower i. . Ul 2, or into the transfer connection I2 and thence into the separating tower 2, through any one or more of the connections I3, I4, I5, and I5 at a rate regulated to maintain a temperature, for example, of 725°--'7'75° F. in the lower part of this tower. Separated liquid tar is discharged from the lower part of this tower through connection I'I and the separated vapor fraction is discharged from the upper part of this tower, to be intro duced into the fractionating tower 3, through In the fractionating tower 3, 25 connection I8. two high boiling condensates are Separated, the higher boiling of these being discharged through connection -I and the lower boiling being dis charged through connection I9. The fractionat 30 ing tower 3 is controlled, for example, to produce as an overhead product a gasoline fraction of desired boiling range, condensed and collected in the condenser 4 and the receiver 5, this control being effected by regulated circulation of a cool > ing medium through the reflux condenser 20 or regulated introduction of a refluxing medium through connection 2| or by these means con jointly. 40.. therefrom through connection I9, is substan tially free from those constituents of the ex panded hot oil products discharged into the sep arating tower 2 of boiling range next lower than, or abutting that of the tar -discharged through plete stripping of the liquid tar separated in the separating tower 2 to which general reference has previously been made. Stocks of boiling range 15 corresponding to that of this intermediate frac tion are as a class appropriate to be used as the cooling medium introduced into` the separating receptacle in accordance with this invention. The provision of a tar leg of cross sectional area sub stantially less than that of the separating recep tacle proper, such as the tar leg 30 in the appa ratus illustrated, materially facilitates the main tenance of a vminimum volume of separated liquid tar in the separating receptacle. By maintain ing the liquid level of separated liquid tar within the tar leg 30, in apparatus such as that illus trated, it is comparatively easy to maintain liq uid discharge through connection I‘I while main taining a volume of separated liquid tar in the 30 separating tower 2 not exceeding 1/2 barrel in operations in which the charging rate to the heat ing coil IIJ exceeds 200 barrels per hour. We claim: 1. In cracking higher boiling petroleum oils 35 to produce gasoline, the improvement which com prises heating a stream of high boiling oil to a A part of the distillate product may be cracking temperature under superatmospheric supplied as a refiuxing medium by means of con nection 22 or a corresponding stock from an extraneous source may be supplied through con pressure, reducing the pressure on the hot oil nection 23, for example. The distillate product is discharged from receiver 5 through connec tion 24 and uncondensed vapors and gases through connection 25. The higher boiling con densate separated in the fractionating tower 3, or part of it, may be supplied to the heating coil I0 through connections 'I and 8 or this higher boiling condensate or any remaining part of it may be discharged through cooler 26. The lower boiling of the two condensates separated in the fractionating tower 3 may, in whole or in part, be supplied to the pump 21 or discharged through cooler 28. A stock to be used as a cooling medium _ in the separating tower 2 may be supplied to pump 21 through connection 29. In carrying out the invention in the apparatus illustrated, for example: 'I'he lower boiling of the two condensates separated in the fractionating tower 3 or a corresponding stock is supplied to the separating tower 2 as a cooling medium, by means of pump 21, and that minimum volume of separated liquid tar necessary to maintain liquid discharge through connection I'I is maintained Usually it is advantageous to introduce that proportion, 65 in the lower part of separating tower 2. ì usually a small proportion, of this fraction nec essary to maintain slight reiluxing into the sep arating tower 2 `through connection I6 and to introduce the balance of the total proportion re quired to maintain the desired temperature in the lower part of the separating tower 2 into the transfer connection I2 through connection I3. The condensate separated as an intermediate 751 fraction in the kfractionating tower 3, discharged 20 products of this heating operation and then in troducing them into a separating receptacle, cool ing the expanded hot oil products by introducing continuously into this receptacle a liquid oil frac tion vaporizing substantially completely therein and substantially free from those constituents of the expanded hot oil products of boiling range abutting that of the tar to be separated in the receptacle, taking‘off vapors from said separating receptacle and subjecting them to a condensing operation thereby forming a condensate including those constituents of ucts of boiling range be separated in said venting direct return the expanded hot oil prod 50» abutting that of the tar to separating receptacle, pre of the last-mentioned con densate to said separating receptacle, maintain ing within the receptacle that minimum volume of separated liquid tar necessary to maintain liquid discharge therefrom, and separately dis charging a vapor fraction and a, liquid tar from the separating receptacle. 2. In cracking higher boiling petroleum oils to produce gasoline, the improvement which com prises heating a stream of high boiling oil to a cracking temperature under superatmospheric pressure, reducing the pressure on the hot oil products of this heating operation and thenin 65 troducing them directly into a separating recep tacle, cooling the expanded hot oil products by introducing continuously into this receptacle a liquid oil fraction vaporizing substantially com pletely therein and substantially free from those constituents of the expanded hot oil products of boiling range abutting that of the tar to- be sepa rated in the receptacle, taking off vapors from said separating receptacle and subjecting them t0 l 2,091,118 ‘ 3 a condensing operation thereby forming a con densate including those constituents of the ex minimum volume of separated liquid tar necessary to maintain liquid discharge therefrom, and Sep panded hot oil products of boiling range abutting arately discharging a vapor fraction and a. liquid that of the tar to be separated in said separating tar from the separating receptacle. receptacle, preventing direct return of the last mentioned condensate to said separating recep tacle, maintaining within the receptacle that EUGENE C. HERTHEL. CARLTON L. SCHMIDT.